Recently, technologies with respect to green vehicles using electrical energy as vehicle power have been actively developed to cope with air pollution and depletion of fossil fuel reserves. Green vehicles include a hybrid electric vehicle, a fuel cell electric vehicle, and an electric vehicle.
In a conventional inverter system for a vehicle for outputting high power, as shown in FIG. 1, multiple switching elements S1 to S6 are connected in parallel to drive a motor in order to output high power. However, in the conventional inverter system, excessive switching and conducting losses occur in the switching elements in a fuel economy driving mode in which power requirements of the motor are relatively low, decreasing vehicle fuel efficiency although high power can be output by connecting the switching elements in parallel. Accordingly, development of an inverter system for vehicles which is able to improve the efficiency as well as power of a vehicle is required.